Personally, I doubt either handheld will be worthwhile. I mean, we're all used to beautiful graphics on our consoles (whether GameCube, PlayStation 2, Xbox) and/or on our PC's that the graphics of these handhelds will seem like the difference between a portable, black and white TV vs. a 20" full-color, plasma TV with 6.1 surround sound playing LOTR on DVD. When I woke up early, got to the store before it opened, and purchased my GBA (not SP), I was thoroughly disappointed. I was expecting Nintendo to do a decent job. IMO, the shape of it was uncomfortable, the buttons were too small and too few, the graphics sucked, and there weren't any worthwhile games for it. Don't get me wrong, I'm not a biased person, but the games I got - Tony Hawk 2, Super Dodgeball Advance, Super Mario Advance, Iridion 3D, Cruisn' Velocity - all were either too easy and beaten in under an hour on the highest difficulty, or were too hard on the easiest to get far at all. And the graphics of the last two listed games were worse than what a monochrome cell phone could do. I was wholly dissatisfied with my purchase that just recently, after not playing it for years, I sold the entire thing, all my 6 GBA games, and my 20 or so GB games and bought a Special Editon Halo Xbox. So, after all this, I doubt either system will be all that great.
Now, look at PDA's. They have some of them so incredible, that I just wonder why they don't incorporate some of that into a portable gaming system. I mean, if it's possible to have millions of colors on a crystal clear screen, fit all that memory and such into such small places (stop the darn cartridges for gosh sakes. If it's possible to get 2 gigs of data on an SD memory card, which is about a hundredth the size of the GBA cartridges and millions of times the capacity, why don't they) and whatnot, why do they still shove utter crap into an uncomfortable, overpriced piece of cheap plastic and sell it as a portable game system?
Money. They want to spend the least amount of money they possibly can on anything they sell, sell it at a super high price that's way over what it's worth, and get as much money out of our pockets as they can. And, since most of America is full of stupid people, the companies have billions of dollars. Thank you stupid people. Maybe if we just refused to buy the stuff until they made it worth our money, we'd get higher quality products for a less amount of money.
Remember, this is just my opinion. Flames are not needed, they just make you look retarded that you can't accept other's opinions.